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Use of otolith shape to inform stock structure in Patagonian toothfish (Dissostichus eleginoides) in the Southwest Atlantic
An analysis of patterns in otolith shape is an effective tool for discriminating between fish stocks. Otolith shape of Patagonian toothfish (Dissostichus eleginoides) and Antarctic toothfish (D. mawsoni) were investigated for geographic variability within seven regions across the Patagonian Shelf, and South Georgia and the South Sandwich Islands (SGSSI). Otolith shape was characterised by their elliptical Fourier coefficients (EFCs), corrected for fish length prior to being analysed, using multivariate methods. Non-metric multidimensional scaling analysis suggested three main groupings: Patagonian Shelf, SGSSI, and the third for Antarctic toothfish. This result was supported by ANOVA-like permutation tests, indicating significant differences in otolith shape between each of these three groupings (P<0.001). Linear discriminant analysis (LDA) cross-validation analyses of the EFCs resulted in otoliths being correctly classified to the sampling region from which they came with an accuracy ranging from 78.95 to 100%. LDA cross-validation analyses on sampling regions within SGSSI and the Patagonian Shelf were able to classify individuals back to their sampling region with an accuracy of over 89.74% and 78.95%, respectively. These results have provided some alternative insights into stock structure of Patagonian toothfish across southern South America, South Atlantic and SGSSI.
MF17327 Accepted 16 January 2018
© CSIRO 2018